Lake Winnipeg Regulation

Lake Winnipeg Regulation is a key to hydropower development on the Nelson River.

Why is regulation necessary?

Lake Winnipeg Regulation provides more reliable flows from the lake for generating stations on the Nelson River in northern Manitoba.

Prior to Lake Winnipeg Regulation, the shallow natural outlet of Lake Winnipeg at Warren Landing was subject to ice blockages in the winter and weed blockages in the summer. The Lake Winnipeg Regulation project constructed new channels to increase the outflow capability from the lake and a control structure 100 kilometres downstream from the lake's outlet. Relative to natural conditions, the new channels provide up to 50 per cent more outflow capacity. Learn about the history of regulation.

Lake Winnipeg Regulation not only provides benefits for power production but also alleviates flooding and drought effects on Lake Winnipeg. Regulation of Lake Winnipeg for these latter purposes had been explored previously, but only became economically feasible with hydropower development on the Nelson.

The project is licensed under the Manitoba Water Power Act. The Licence sets requirements for the control of outflows from Lake Winnipeg, based on its elevation:

When the lake level is between 711 to 715 feet, we set outflows as required for power production on the Nelson River.

When the lake level is above 715 feet, we must operate at maximum discharge until 715 feet is reached.

When the lake level is below 711 feet, we must operate outflow as ordered by the Minister responsible for the Water Power Act.

About Lake Winnipeg

Lake Winnipeg is the:

13th largest lake in the world;

11th largest fresh water lake in the world by volume;

10th largest fresh water lake in the world by area;

7th largest lake in North America.

Lake Winnipeg collects run-off water from a 1,000,000 square kilometre drainage basin, which extends from the Canadian Rockies in western Canada to within 19 km of Lake Superior in eastern Canada, and south to 4 states in the USA.

The waters of Lake Winnipeg flow north and leave the lake via the Nelson River, which eventually flows into Hudson Bay. The main tributaries of Lake Winnipeg are the Winnipeg and Saskatchewan rivers. Combined, these 2 rivers account for 75 per cent of the inflow, while the waters from the Red, Dauphin, Bloodvein, and Berens rivers, plus other smaller tributaries, make up the remaining 25 per cent.

The natural inflows to Lake Winnipeg are greatest in the spring and summer, due to the snow melt during warmer weather combining with the naturally heavier rainfalls in spring and early summer. By fall, the tributary waters abate as a result of drier conditions. With winter's onset, inflows decrease as snow does not contribute to the runoff until the following spring. Because of its large surface area (24,420 km2), Lake Winnipeg's level rises and falls very slowly as a result of the difference between inflow and outflow.

Despite the increased outflow capacity created by Lake Winnipeg Regulation, the amount of water that can flow into Lake Winnipeg far exceeds what can flow out. Three major rivers and a host of smaller tributaries flow into the lake and only one river, the Nelson, flows out.